oil separator

JBINTX

Goblin Guru
So there are plenty of references to the build up of carbon and gunk on the intake valves. Several videos are available about walnut blasting and such. Of course, the emission restrictions drove many of the systems that did not exist on engines years ago. I think we are all deleting the EVAP system. That one seems pretty straight forward. The PCV is a little different and maybe a little more complicated. I understand the need to vent the build up of pressure in the crank case. But, I do not think that the best place to put oil vapor is back into the intake - especially without the fuel injection spray to wash it off and deter from the build up. Probably not many arguments there. So, what is everyone doing to eliminate this issue? If anything?

I found a pretty in-depth solution over on CobaltSS.net (LNF PCV Anti-coking drain back system)
https://www.cobaltss.net/forums/2-0l-lnf-performance-tech-153/lnf-pcv-anti-coking-drain-back-system-289225/
Powell Race Parts seems to have designed a pretty involves system. Much more than just a hose to a catch can and a return hose, at least. Anyone familiar with this specific system? They do not seem to have it available for sale on their website. Is there now a better alternative solution?
 

Indy Lonnie

Well-Known Member
I investigated that setup. The major thing that turned me off is that all blow-by will be recirculated back into the oil. That would include any moisture and burnt/unburnt fuel ect. I didn't want any of that being recirculated into my oil.
 

Indy Lonnie

Well-Known Member
Still researching. I'm not driving the car in sub freezing temps right now, so I have some time. I plan to remove the intake and clean the valves with CRC within the next month. I'm not sure how much build-up is there and if regular cleaning by spraying down the intake track will keep it clean once deep cleaned with the intake off. I still have questions too...
There is a video of a guy blasting his valves with walnut media. He actually recommended just spray cleaning with a tooth brush in the Cobalt forums after the mess it made with the walnut shells. I think that speaks volumes...

Can't wait for the temps to break. There was a SCCA autocross meet yesterday that I was invited to and passed on. It was 29 degrees when I needed to leave yesterday morning. A little too cold!
 

Briann1177

Goblin Guru
I'm going with the same treatment plan but with the Seafoam intake cleaner. I just wish I could find a way to hold the RPM at 2k and spray without the need of a helper.
 

Indy Lonnie

Well-Known Member
I read somewhere on the web that GM doesn't recommend SeaFoam, for what that is worth. GM does make their own top end cleaner...
 

JBINTX

Goblin Guru
I know this topic is pretty active right now. @Torchandregdoc has been flying on it. I hope a complete understanding of the vacuum lines is imminent.
Like most others, I found the oil in the intake from the PCV valve. I have yet to confirm how much oil may be coming further upstream in the air flow from the turbo. I think it is way less.
Let me ask my hypothetical question like this. IF the PCV were external, wouldn't inserting a oil/air separator or simple catch can after the PCV and then run the outlet right back to the intake be a good solution to eliminate / stop oil from getting to the intake?
 

Briann1177

Goblin Guru
Yes. I haven't really researched this yet but I think v3 of Powell's Racing oil separator does something along this line
 

JBINTX

Goblin Guru
Yes. I haven't really researched this yet but I think v3 of Powell's Racing oil separator does something along this line
Funny. I just spoke to John Powell. Nice guy. He will be sending me a quote with pics and info on his solution. He has been involved with this issue dating way back to 2012. I have been thinking about it for about 3 weeks now. I do know that I do NOT know as much as him!!.... :)
 

JBINTX

Goblin Guru
John Powell has been around this block way more times than me. As a matter of fact, I just showed up! ;)
I am still waiting on info directly from him today on the system as he sells it presently, but in the mean time, I found this below. Pretty in-depth explanation. Apologies ahead of time for the formatting of it.

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From the Powell race shop ; the next mod.Advanced PCV control. Its a PCV revision to attempt fixing the DI coking problem There will be two versions; one for LNF Cobalts and one for LSJ. The mounting brackets and hose lengths will be different between LNF and LSJ; the HHR SS is the same as the Cobalt SS . The install procedure has a choice of tapping into the existing OEM PCV hose, or removing it and installing a different fitting in the rocker cover.The LSJ DOES NOT HAVE A COKING ISSUE its not a DI engine, but the LSJ PCV is a two way system and is not very effective and some S/C cars pop dipsticks out as the crank case pressure builds up at high revs. BUY IT BUT DONT FORGET US... One thing about this, the way we sell it will be different from the way most vendors sell things. Not to drive everyone crazy about it, simply understand that I want you to keep track and feedback to us, how your car is now, and how it is after time with the PCV upgrade you got from Powell raceshop. It kinda makes our customers a sort of a development test fleet. The engineering in this mod is sound, the ideas have good science, logically it should work, and the execution is well made, not cheap. But we need to see how it works, as we have only limited experience that says "yup it looks like its working." Normally if I were working for a manufacturer, it would go in a durability test fleet that works 24/7 on a specific driving cycle routine , to get long term view of what is going on in a field test. SO HOW WILL THIS UPGRADE WORK FOR YOU? Please understand that for the LNF group, there is a WORLD WIDE issue with most every direct injection gasoline engine with inlet valve coking. Basically, excess oil in the PCV system ends up being deposited on the inlet valves, and with DI unlike port injection, there is no “washing” of the inlet valves with a fuel air charge. There is no one single solution, although we have found good gains with the PCV upgrade so far. There are other important things to consider. The suggested changes for your car include: • using low ash engine oil • change in your driving routine, avoiding low rev/high boost driving. • always use tier one gasoline • always use 93 octane or better • Some of our customers and friends have fresh clean valves in their cars thanks to warranty, and if not, a borescope snapshot of what they look like For the record, proper installation of any catch can or PCV upgrade is important. A catchcan on the fresh air side is silly. For the LNF, the OEM system has: • On the fresh air side running post filter and pre turbo impeller; a check valve in the hose (thats the orifice) and it lets air in to the engine. This inlet air path goes directly to the base of the engine and is sealed from the upper cylinder head. • There is another vent route out through the head into the inlet manifold. There is a check valve in the inlet manifold vent path, so the engine on vacuum ( off boost) can breathe fumes into the inlet manifold. The check valve there closes the moment the inlet is not pulling vacuum. • There is a vent tube with an internal orifice on the dirty side, it vents to the turbo on the intake side. • There is a “floor” in the dirty side route in the rocker cover with horizontal seperators Catch cans without a seperator in two chambers really just become an accumulator of oil. The idea is for the oil laden air on the dirty side to pass through the media ( or spill plates) so the air can leave the oil behind and then be sent on to the original routing. Then the question is, what to do with the accumulated oil? it needs a place to go, and draining it after every track session or every week on the street onto your driveway or into a plastic bottle is not a good way to do it. • I have a way and it makes the system better, while preserving the stock PCV operation which is very important. If you vent the pcv to atmosphere with a filter like a hot rod vent cap, all bets are off and the pcv system will not work at all as intended PCV FUNCTION The pcv orifice sizes (there is more than one ) are chosen to keep the crankcase pressure negative by a small amount under all operating conditions. Under light load, the turbo inlet venturi effect is just enough to cause a depression and pull air through the crankcase from the fresh clean air duct tube. The check valve becomes an “orifice” to control depression. Under high load where the piston blow-by becomes significant, the fresh passage is stopped with a check valve. This is to prevent back flow. The venturi effect of the turbocharger inlet is sufficient to pull in 100% of the piston blow by, plus pull the crankcase pressure 2 to 3 kPa . negative as calibrated in balance with the fresh air check valve. Crankcase pressure should be reasonably uniform. Draining the separated oil back into the crankcase in a similar manner to the turbo oil drain was required. We took care to make a return to avoid crank oil whip and place the drain back oil in a relatively undisturbed location. This was not easy, as we are only talking a few kPa delta to keep flows going in the right direction. COKING Where it starts to fall apart , is when the gradual build up of coked oil on the inlet valves starts to inhibit proper engine operation, and it becomes a circle jerk; the more build up the more oil gets kicked through the pcv, the more oil, the more build up etc. Also if there is an aftermarket tune,(few are very good in my opinion) and there is a lot more fuel, timing and combustion pressure being thrown at the motor, it is possible that the piston rings and ring lands and skirts will wear really fast and then blowby (pressure in the crankcase) becomes so great the pcv system just cant deal with it. No one thing will fix this issue entirely: driving cycles, fuel quality and octane, low ash engine oil are all important additional factors to consider. The driving cycle. The driving cycle I refer to, is to avoid low rev high boost situations , extended low rev cruising and short 1-3 mile start /stop / park driving. Add long idling time in winter as well; the driving cycles may contribute to low inlet valve temperature. All these things I have listed can influence di valve coking in this engine. A techron fuel additive may help if tier 1 gasoline is not always available.
 

JeffsGoblin

Goblin Guru
Please don't forget to ask him about LSJ for us SS/SC guys. It sounds like there isn't difference in the product between a LNF and LSJ, but was hoping he could confirm.
 

JBINTX

Goblin Guru
All: I received two lengthy documents from John Powell. I feel I must respect his confidentiality statement that forbids me from re-posting the contents in whole here. Sorry. Looks like I can pull out some parts, though. You are welcome to inquire directly as well.

[email protected]
(LNF PCV Anti-coking drain back system)

I can tell you he has revised his solution several times over more than a five year period with a lot of real world miles for feedback. Weird part is they did not give me the price of the kit or a quote. (???!!) I replied back for that info. Will share that when received.

Concerning the LSJ: Here is an excerpt.
  • LSJ engines show the same issue with oil wicking past the gasket (on the intake manifold to the head). It doesn’t make for any issues, in either case, but its an indication how much blow by oil from the PCV is getting onto the valves.
  • In the LSJ with port fuel EFI there is clear evidence of the air fuel mixture is washing the ports and the inlet valve stems.
  • The LSJ DOES NOT HAVE A COKING ISSUE it’s not a DI engine, but the LSJ PCV is a two-way system and is not very effective and some S/C cars pop dipsticks out as the crank case pressure builds up at high revs.
edit: That's not to say you LSJ guys still ideally would like to not be burning any oil, though.
 
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Parson Green

Well-Known Member
All: I received two lengthy documents from John Powell. I feel I must respect his confidentiality statement that forbids me from re-posting the contents in whole here. Sorry. Looks like I can pull out some parts, though. You are welcome to inquire directly as well.

[email protected]
(LNF PCV Anti-coking drain back system)

I can tell you he has revised his solution several times over more than a five year period with a lot of real world miles for feedback. Weird part is they did not give me the price of the kit or a quote. (???!!) I replied back for that info. Will share that when received.

Concerning the LSJ: Here is an excerpt.
  • LSJ engines show the same issue with oil wicking past the gasket (on the intake manifold to the head). It doesn’t make for any issues, in either case, but its an indication how much blow by oil from the PCV is getting onto the valves.
  • In the LSJ with port fuel EFI there is clear evidence of the air fuel mixture is washing the ports and the inlet valve stems.
  • The LSJ DOES NOT HAVE A COKING ISSUE it’s not a DI engine, but the LSJ PCV is a two-way system and is not very effective and some S/C cars pop dipsticks out as the crank case pressure builds up at high revs.
edit: That's not to say you LSJ guys still ideally would like to not be burning any oil, though.
Dipsticks don't lie and the dipstick on our factory-stock LSJ engine is telling us two important facts.

First, that we have near-zero oil consumption and second that the oil is staying as clean as the day it was last changed.

WRT any kind of catch-can mod, does that put us solidly into the if-it-ain't-broke-don't-fix-it realm? Methinks yes.
 
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JeffsGoblin

Goblin Guru
I think you really have to look at the intake manifold and the laminova cores to see how gunked up they are with oil. Mine were pretty bad, so cleaning them took awhile. I would prefer not to have the oil coming from the valve cover port and back into the intake, so I may install a catch can or just vent out to the atmosphere. I'm also waiting to hear what Powell Racing says.
 

Parson Green

Well-Known Member
I think you really have to look at the intake manifold and the laminova cores to see how gunked up they are with oil. Mine were pretty bad, so cleaning them took awhile. I would prefer not to have the oil coming from the valve cover port and back into the intake, so I may install a catch can or just vent out to the atmosphere. I'm also waiting to hear what Powell Racing says.
Did you also find gunk in your throttle body and thereabouts? If not, the gunk you found in your IM (& the intercooler) probably would not have been intercepted by a catchcan placed in the location you're describing.

(The IM and intercooler on our engine were, btw, free of gunk.) (Proof, btw, that the stock crankcase-venting config had been doing an excellent job.)
 
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